Method of making soldering irons



p 21, 1965 H. J. M. VAN EMBDEN 3,206,834

METHOD OF MAKING SOLDERING IRONS Original Filed Sept. 14, 1960 2 (copper with metallic wire F INVENTOR.

HENDRICK J. M. VAN EMBDEN BY ELM 1 AGENT T' United States Patent METHOD OF MAKING SOLDERING IRONS Hendrick Johannes Meerkamp van Ernbden, Eindhoven,

Netherlands, assignor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Original application Sept. 14, 1960, Ser. No. 55,973, now

Patent No. 3,157,143, dated Nov. 17, 1964. Divided and this application Oct. 2, 1964, Ser. No. 404,549

2 Claims. '(Cl. 29'155.5)

My invention relates to soldering irons and particularly to copper tips used in the connection therewith, and to a method of making the same.

The instant application is a division of application Serial No. 55,973, filed September 14, 1960 and now Patent No. 3,157,143.

The copper tips used for soldering have the disadvantage that they are liable to dissolve in the liquid solder or to take up the same. As a result the tip, or at least the end thereof, becomes comparatively soft, and thus is easily deformed by any mechanical force exerted thereon during the soldering. This difficulty is particularly prevalent when it becomes necessary to rub the tip on the metal to be soldered in order to make the solder adhere to the metal. This occurs, for instance, in soldering to aluminum, having an aluminum oxide surface coating to which the solder does not readily adhere. By scratching or rubbing the aluminum with the soldering tip the oxide layer is removed and the soldering can be readily carried out without the possibility of the aluminum oxidizing again. However, as stated above, this rubbing deforms the soldering tip and greatly reduces the life thereof. In addition the smooth surface of the soldering tip makes it difficult to remove the oxide layer by rubbing the tip on the metal.

In accordance with the invention the above disadvantages are overcome by distributing within the copper of the soldering tip a quantity of wire formed of a metallic material, i.e. a metal or alloy, which has a melting point above that of copper, for instance about 1200" C., and higher and which is substantially insoluble in molten copper. Molybdenum and tungsten are particularly suitable for this purpose although other suitable materials are their alloys, alloys of Mo acid W.

The metallic wire, which may be of various crosssections and thicknesses of usually between about 20 to 150 is arranged in the copper so that the ends thereof will project slightly from the active surface of the tip. This may be effected by means of arranging the Wire at random, but I have found that the best results are obtained when the wire extends mainly in a direction perpendicular to the active surface of, or in the axial direction of, the soldering tip.

The ends of the metallic wire, which project slightly from the active surface of the tip, make it easy to scratch the metal to be soldered through the fluid solder, and also through an intermediate layer, such as a layer of aluminum oxide, so that the solder will readily adhere to the metal. The copper tip with the metallic wire therein will not be softened at all, or only to a very slight extent, due to the'heat, solder and mechanical forces applied, with the result, that the tip will have a long life.

In accordance with the method of the invention the soldering tips are formed by filling a metal tube with a mass of the metallic wire and then filling the remaining spaces with molten copper by capillary action. The cooled filled tube is then reduced in diameter by elongating it for instance by hammering or drawing, so as to arrange the filaments in the axial direction after which desired lengths of the tube are cut off to form the tips.

In order that the invention may be clearly understood and readily carried into effect we shall describe the same in more detail with reference to the accompanying drawing in which:

FIGURE 1 is a sectional view of a metal tube filled with a mass of wire,

FIG. 2 is a section view of the tube of FIGURE 1 at one stage of the method of the invention,

FIG. 3 is a section view of a tube from which soldering tips are made, and

FIG. 4 is a sectional side view of a soldering tip according to the invention.

As shown in FIGURE 1, a tube 1 of a metal which is only slightly attacked by solder, for instance stainless steel, and which has an outside diameter of about 16 mms. and an inside diameter of about 13 mms., is filled with a mass of tungsten or molybdenum wire having a thickness of about 40 microns and arranged at random. As shown in FIG. 2, the end of the filled tube of FIGURE 1 is then immersed in a pool of molten copper 3 contained in a basin 4 so that the molten copper will rise by capillary action up into the tube 1 and :fill the voids in the wire mass 2. After being cooled, the tube 1 with the copper-metal wire mass, therein is reduced in diameter, for example from about 16 mms. to 8 mms., for instance by hammering or :a drawing operation, to thereby obtain the structure shown in FIG. 3 in which metallic wire 2 is arranged in a general axial direction. The tube of FIG. 3 is then cut into desired lengths to form soldering tips, and because of its axial arrangement the metallic wire 2 will in general extend generally perpendicularly to the surfaces of the tips.

The thickness of the tungsten and molybdenum wire may be between about 20 1. to 150 but I have found that excellent results are obtained with wire having a thickness between 40 and microns. As to the amount of the metallic wire used, I have found that in general the ratio between the weight of the copper and the wire should lie between about 3:7, and 4:1, and that good results are obtained when using copper and tungsten or molybdenum in a ratio of about 1:1.

Tips cut from the filled tube shown in FIG. 3 may be used without removing the envelope 1, for example in automatic soldering in which the bit in rotated around its axis. However in other cases the surrounding tube may be at least partly removed. For example, a soldering tip such as shown in FIG. 4, which is suitable for use with the usual hand electric soldering irons, is formed by cutting a piece from the filled tube of FIG. 3 and machining the same to form the conical-shaped tip. In some cases it is desirable to remove all of the tube 1.

While I have described my invention in connection with special examples and particularly materials, I do not desire to be limited thereto as obvious modifications will readily present themselves to one skilled in this art.

What is claimed is:

1. A method of making soldering tips comprising the steps of arranging within a metallic tube, a mass of random extending Wire of a metallic material substantially insoluble in molten copper and having a melting point higher than that of copper, filling the spaces Within the tube With molten copper, cooling the tube to solidify the copper, elongating the filled tube to arrange the Wire generally in the axial direction thereof, and forming soldering tips from the elongated tube.

2. A method of making soldering tips comprising the steps of arranging Within a metallic tube a mass of raninsoluble in molten copper and having a melting point higher than that of copper, inserting one end of the tube in molten copper to thereby fill the spaces in the tube by capillary action, cooling the tube to solidify the copper, drawing the filled tube to a reduced diameter to thereby arrange the Wire generally in the axial direction thereof and machining soldering tips from the elongated tube.

No references cited.

dom-extending wire of a metallic material substantially 10 WHITMORE A, WILTZ, Primary E amine 

1. A METHOD OF MAKING SOLDERING TIPS COMPRISING THE STEPS OF ARRANGING WITH A METALLIC TUBE, A MASS OF RANDOM EXTENDING WIRE OF A METALLIC MATERIAL SUBSTANTIALLY INSOLUBLE IN MOLTEN COPPER, AND HAVING A MELTING POINT HIGHER THAN THAT OF COPPER, FILLING THE SPACES WITHIN THE TUBE WITH MOLTEN COPPER, COOLING THE TUBE TO SOLIDIFY THE COPPER, ELONGATING THE FILLED TUBE TO ARRANGE THE WIRE GENERALLY IN THE AXIAL DIRECTION THEREOF, AND FORMING SOLDERING TIPS FROM THE ELONGATED TUBE. 